System and method of producing and separating metals and alloys

ABSTRACT

A system and method of producing an elemental material or an alloy from a halide of the elemental material or halide mixtures. The vapor halide of an elemental material or halide mixtures are introduced into a liquid phase of a reducing metal of an alkali metal or alkaline earth metal or mixtures thereof present in excess of the amount needed to reduce the halide vapor to the elemental material or alloy resulting in an exothermic reaction between the vapor halide and the liquid reducing metal. Particulates of the elemental material or alloy and particulates of the halide salt of the reducing metal are produced along with sufficient heat to vaporize substantially all the excess reducing metal. Thereafter, the vapor of the reducing metal is separated from the particulates of the elemental material or alloy and the particulates of the halide salt of the reducing metal before the particulate reaction products are separated from each other.

RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 10/530,775,filed Jan. 18, 2006, which pursuant to 37 C.F.R. 1.78(c), claimspriority based on U.S. Provisional Application Ser. No. 60/416,630,filed Oct. 7, 2002, and U.S. Provisional Application Ser. No.60/328,022, filed Oct. 9, 2001, the entirety of each hereby expresslyincorporated herein by reference.

The present application is also a continuation-in-part of U.S. Ser. No.10/526,918, filed Nov. 14, 2005, which pursuant to 37 C.F.R. 1.78(c),claims priority based on U.S. Provisional Application Ser. No.60/408,932, filed Sep. 7, 2002, U.S. Provisional Application Ser. No.60/408,925, filed Sep. 7, 2002, and U.S. Provisional Application Ser.No. 60/408,933, filed Sep. 7, 2002, the entirety of each herebyexpressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to the production and separation of elementalmaterial from the halides thereof and has particular applicability tothose metals and non metals for which a reduction of the halide to theelement is exothermic. Particular interest exists for titanium, and thepresent invention will be described with particular reference totitanium, but is applicable to other metals and non metals such asaluminum, arsenic, antimony, beryllium, boron, tantalum, gallium,vanadium, niobium, molybdenum, iridium, rhenium, silicon osmium,uranium, and zirconium, all of which produce significant heat uponreduction from the halide to the metal. For the purposes of thisapplication, elemental materials include those metals and non metalslisted above or in Table 1 and the alloys thereof.

This invention is an improvement in the separation methods disclosed inU.S. Pat. No. 5,779,761, U.S. Pat. No. 5,958,106 and U.S. Pat. No.6,409,797, the disclosures of which are incorporated herein byreference. The above-mentioned '761, '106 and '797 patents disclose arevolutionary method for making titanium which is satisfactory for itsintended purposes and in fact continuously produces high grade titaniumand titanium alloys. However, the method described in the '761 patent,the '106 and the '797 patent produces a product which includes excessliquid reducing metal. The present invention resides the discovery thatby maintaining the excess reducing metal in vapor phase by controllingthe temperature of reaction and the amount of excess reducing metal, theseparation of the produced material is made easier and less expensive.

More particularly, it has been found that by controlling the amount ofexcess metal, the temperature of the reaction products of the exothermicreaction can be maintained between the boiling point of the reducingmetal and the boiling point of the salt produced which causes excessreducing metal to remain in the vapor phase after the reactionfacilitating the later aqueous separation of the salt produced from theelemental material or alloy. This results in a substantial economicsavings and simplifies the separation and recovery process.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention is to provide amethod and system for producing metals or non metals or alloys thereofby an exothermic reaction between vapor phase halides and a liquidreducing metal in which the reducing metal is maintained in the vaporphase after the exothermic reaction in order to facilitate separation ofthe reaction products and the products made thereby.

Yet another object of the present invention is to provide an improvedmethod and system for producing elemental materials or an alloy thereofby an exothermic reaction of a vapor halide of the elemental material ormaterials or halide mixtures thereof in a liquid reducing metal in whicha sweep gas is used to separate the reducing metal in the vapor phasefrom the products of the exothermic reaction and the products madethereby.

The invention consists of certain novel features and a combination ofparts hereinafter fully described, illustrated in the accompanyingdrawings, and particularly pointed out in the appended claims, it beingunderstood that various changes in the details may be made withoutdeparting from the spirit, or sacrificing any of the advantages of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the invention, thereis illustrated in the accompanying drawings a preferred embodimentthereof, from an inspection of which, when considered in connection withthe following description, the invention, its construction andoperation, and many of its advantages should be readily understood andappreciated.

FIG. 1 is a schematic representation of a system for practicing onemethod of the present invention.

FIG. 2 is a flow sheet of a representative example of the process aspracticed in the system of FIG. 1 showing various flow rates andtemperatures in the system.

FIG. 3 is a schematic representation of another system for practicinganother embodiment of the present invention.

FIG. 4 is a schematic representation of another embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 of the drawings, there is disclosed a system 10for the practice of the invention. The system 10 includes a reactor 15generally vertically displaced in this example in a drop tower vessel16, the drop tower 16 having a central generally cylindrical portion 17,a dome top 18 and a frustoconical shaped bottom portion 19. A productoutlet 20 is in communication with the frustoconical portion 19. Thereactor 15 essentially consists of an apparatus illustrated in FIG. 2 ofU.S. Pat. No. 5,958,106 in which a tube through which liquid metal flowsas a stream has inserted thereinto a halide(s) vapor so that the vaporhalide(s) is introduced into the liquid reducing metal below the surfaceand is entirely surrounded by the liquid metal during the ensuingexothermic reaction.

A reducing metal inlet pipe 25 enters the reactor 15 near the top 18 anda vapor halide inlet 30 also enters the drop tower 16 near then top 18.However, it will be understood by a person of ordinary skill in the artthat a variety of configurations of inlet conduits may be used withoutdeparting from the spirit and scope of the present invention.

As illustrated, there is an overhead exit line 35 through which vaporleaving reactor 15 can be drawn. The overhead exit line 35 leads to acondenser 37 where certain vapors are condensed and discharged throughan outlet 38 and other vapor or gas, such as an inert gas, is pumped bya pump 40 through a heat exchanger 45 (see FIG. 2) and line 41 into thedrop tower 16, as will be explained.

For purposes of illustration, in FIG. 1 there is shown a reducing metalof sodium. It should be understood that sodium is only an example ofreducing metals which may be used in the present invention. The presentinvention may be practiced with an alkali metal or mixtures of alkalimetals or an alkaline earth metal or mixtures of alkaline earth metalsor mixtures of alkali and alkaline earth metals. The preferred alkalimetal is sodium because of its availability and cost. The preferredalkaline earth metal is magnesium for the same reason.

The preferred halide(s) to be used in the process of the presentinvention is a chloride again because of availability and cost. Themetals and non-metals which may be produced using the subject inventionare set forth in Table 1 hereafter; the alloys of the metals andnon-metals of Table 1 are made by introducing mixed halide vapor intothe reducing metal.

TABLE 1 FEEDSTOCK HEAT kJ/g TiCl₄ −5 AlCl₃ −5 SbCl₃ −4 BeCl₂ −6 BCl₃ −8TaCl_(s) −4 VCl₄ −6 NbCl₅ −5 MoF₅ −10 GaCl₃ −5 UF_(s) −4 ReFs −8 ZrCl₄−4 SiCl₄ −11

All of the elements in Table 1 result in an exothermic reaction with analkali metal or alkaline earth metal to provide the halide(s) of thereducing metal and the metal or alloy of the halide introduced into thereducing metal. Ti is discussed only by way of example and is not meantto limit the invention. Because of the large heat of reaction, there hasbeen the problem that the reaction products fuse into a mass of materialwhich is difficult to process, separate and purify. Discussions of theKroll and Hunter processes appear in the patents referenced above.

The patents disclosing the Armstrong process show a method of producinga variety of metals and alloys and non-metals in which the heat ofreaction resulting from the exothermic reaction is controlled by the useof excess liquid reducing metal and the reaction proceedsinstantaneously by introducing the metal halide into a continuous phaseof liquid reducing metal, otherwise described as a liquid continuum. Theuse of a subsurface reaction described in the Armstrong process has beenan important differentiation between the batch processes and othersuggested processes for making metals such as titanium and the processdisclosed in the Armstrong et al. patents and application.

Nevertheless, the use of excess liquid reducing metal requires that theexcess liquid metal be separated before the products can be separated.This is because the excess liquid reducing metal usually explosivelyreacts with water or is insoluble in water whereas the particulateproducts of the produced metal and the produced salt can be separatedwith water wash.

By way of example, when titanium tetrachloride in vapor form is injectedinto sodium liquid, an instantaneous reaction occurs in which titaniumparticles and sodium chloride particles are produced along with the heatof reaction. Excess sodium absorbs sufficient heat that the titaniumparticles do not sinter to form a solid mass of material. Rather, afterthe excess sodium is removed, such as by vacuum distillation suggestedin the aforementioned Armstrong patents, the remaining particulatemixture of titanium and sodium chloride can be easily separated withwater.

Nevertheless, vacuum distillation is expensive and it is preferred tofind system and method that will permit the separation of theparticulate reaction products of the reaction directly with waterwithout the need of preliminary steps. This has been accomplished in thepresent invention by the discovery that by judiciously limiting theamount of excess reducing metal present, the boiling point of theproduced salt will be the limiting temperature of the reaction and solong as the temperature of reaction products is maintained above theboiling point of the reducing metal and below the boiling point of theproduced salt, any excess reducing metal present will remain in thevapor phase which can be efficiently and inexpensively removed so thatthe particulates accumulating at the bottom 19 of the reaction vessel ordrop tower 16 are entirely free of liquid reducing metal, therebypermitting the separation of the particulate reaction products withwater, obviating the need for a separate vacuum distillation step.

As illustrated in FIG. 2, the halide gases of the elemental material oralloy to be made such as titanium tetrachloride, come from a storage orsupply 31. The titanium tetrachloride is fed, in one specific exampleonly, at the rate indicated on FIG. 2, to a boiler 32 and from there viathe inlet pipe 30 to the reactor 15. The sodium reducing metal is fed,in one specific example only at the rate indicated on FIG. 2, from astorage container 26 through an inlet line 25 to the reactor 15. Asbefore stated, the liquid sodium flows in the specific example asindicated on FIG. 2 in a 50% excess quantity of the stoichiometricamount needed to convert the titanium tetrachloride to titanium metaland as indicated in FIG. 2 at a temperature of 200° C. at which thesodium is liquid.

In the reactor 15, as previously taught in the Armstrong patents andapplication, the continuous liquid phase of sodium is established intowhich the titanium tetrachloride vapor is introduced and instantaneouslycauses an exothermic reaction to occur producing large quantities ofheat, and particulates of titanium metal and sodium chloride. Theboiling point of sodium chloride is 1465° C. and becomes the upper limitof the temperature of the reaction products. The boiling point of sodiumis 892° C. and is the lower limit of the temperature of the reactionproducts to ensure that all excess sodium remains in the vapor phaseuntil separation from the particulate reaction products. A choke flownozzle also known as a critical flow nozzle is well known and used inthe line transmitting halide vapor into the liquid reducing metal, allas previously disclosed in the '761 and '106 patents. It is critical forthe present invention that the temperature of the reaction products aswell as the excess reducing metal be maintained between the boilingpoint of the reducing metal, in this case sodium, and the boiling pointof the salt produced, in this case sodium chloride.

The vapors exiting the reactor 15 are drawn through exit line 35 alongwith an inert sweep gas introduced through the inert gas inlet 41. Theinert gas, in this example argon, may be introduced at a temperature ofabout 200° C., substantially lower than the temperature of the reactionproducts which exit the tower 16 at 800° C. The argon sweep gas flows,in the example illustrated in FIG. 1, countercurrently to the directionof flow of the particulate reaction products. The sodium vapor is sweptby the argon into the outlet 35 along with whatever product fines areentrained in the gas stream comprised of argon and sodium vapor at about900° C. and transmitted to the condenser 37. In the condenser 37, asshown in FIG. 2, heat exchange occurs in which the sodium vapor iscooled to a liquid at about 400° C. and recycled to the sodium feed orinlet 25 via line 38 and the argon is cooled from 400° C., thetemperature at which it exits the condenser 37 by a cooler 45 to the200° C. temperature at which it is recycled as shown in FIG. 2. It isseen therefore, that the inert gas preferably flows in a closed loop andcontinuously recirculates as long as the process is operational. Theproduct fines present in the condenser 37 will be removed by filters(not shown) in both the sodium recycling line 38 and in the line 39exiting the condenser 37 with the inert gas.

As the inert gas moves upwardly through the vessel or drop tower 16,there is contact between the colder inert gas and the reactionparticulates which are at a higher temperature. As seen from FIG. 2, thesodium vapor exits the drop tower 16 at a temperature of about 900° C.while the particulate product exits the reactor 15 at a temperature notgreater than 1465° C. After being cooled by contact with the argon gas,the particulate product, in this example, is at a temperature of about800° C. at the exit or product outlet 20. The product 20 which leavesthe vessel 16 at about 800° C. enters a cooler 21, see FIG. 2, to exittherefrom at 50° C. Thereafter, the product is introduced through line22 to a water wash 50 in which water is introduced into a containerthrough a line 51 and brine exits from the water wash 50 via line 53.The titanium particulates exit from the water wash through a line 52 fordrying and further processing.

It should be understood that although titanium is shown to be theproduct in FIGS. 1 and 2 any of the elements or alloys thereof listed inTable 1 may be produced by the method of the present invention. The mostcommercially important metals at the present time are titanium andzirconium and their alloys. The most preferred titanium alloy fordefense use is 6% aluminum, 4% vanadium, the balance substantiallytitanium. This alloy known as 6:4 titanium is used in aircraft industry,aerospace and defense. Zirconium and its alloys are important metals innuclear reactor technology. Other uses are in chemical processequipment.

The preferred reducing metals at the present time because of cost andavailability are sodium of the alkali metals and magnesium of thealkaline earth metals. The boiling point of magnesium chloride is 1418°C. and the boiling point of magnesium is 1107° C. Therefore, ifmagnesium were to be used rather than sodium as the reducing metal, thenpreferably the product temperature would be maintained between theboiling point of magnesium and the boiling point of magnesium chloride,if the chloride salt of the metal or alloy to be produced were to beused. The chlorides are preferred because of cost and availability.

One of the significant features of the present invention is the completeseparation of reducing metal from the particulate reaction products asthe reaction products leave the reactor 15 thereby providing at thebottom of the drop tower 16 a sodium free or reducing metal-free productwhich may then be separated with water in an inexpensive anduncomplicated process. If liquid sodium or other reducing metal istrapped within the product particulates, it must be removed prior towashing. Accordingly, the invention as described is a significantadvance with respect to the separation of the metal or alloyparticulates after production disclosed in the aforementioned Armstronget al. patents and application.

Referring to FIG. 3, there is disclosed another embodiment of thepresent invention system 110 which includes a reactor 115 disposedwithin a drop tower 116 having a cylindrical center portion 117, a dometopped portion 118 and a frustoconical bottom portion 119 connected to aproduct outlet 120. A plurality of cooling coils 121 are positionedaround the frustoconical portion 119 of the drop tower 116 for a purposeto be explained.

As in the system 10 shown in FIGS. 1 and 2, there is a metal halideinlet 130 and a reducing metal inlet 125 in communication with thereactor 115 disposed within the drop tower 116. An overhead exit line135 leads from the dome top portion 118 of the drop tower 116 to acondenser 137 in fluid communication with a pump 140. A liquid reducingmetal and product fine outlet 138 is also provided from the condenser137.

In operation, the system 110 is similar to the system 10 in that aliquid reducing metal, for instance sodium or magnesium, is introducedvia inlet 125 from a supply thereof at a temperature above the meltingpoint of the metal, (the melting point of sodium is 97.8° C. and for Mgis 650° C.) such as 200° C. for sodium and 700° C. for Mg. The vaporhalide of the metal or alloy to be produced, in this case titaniumtetrachloride, is introduced from the boiler at a temperature of about200° C. to be injected as previously discussed into a liquid so that theentire reaction occurs instantaneously and is subsurface. The productscoming from the reactor 115 include particulate metal or alloy, excessreducing metal in vapor form and particulate salt of the reducing metal.In the system 110, there is no sweep gas but the drop tower 116 isoperated at a pressure slightly in excess of 1 atmosphere and this byitself or optionally in combination with the vacuum pump 140 causes thereducing metal vapor leaving the reactor 115 to be removed from the droptower 116 via the line 135. A certain amount of product fines may alsobe swept away with the reducing metal vapor during transportation fromthe drop tower 116 through the condenser 137 and the liquid reducingmetal outlet 138. A filter (not shown) can be used to separate any finesfrom the liquid reducing metal which is thereafter recycled to the inlet125.

Cooling coils 121 are provided, as illustrated on the bottom 119 of thedrop tower 116. A variety of methods may be used to cool the drop tower116 to reduce the temperature of the product leaving the drop tower 116through the product outlet 120. As illustrated in FIG. 3, a plurality ofcooling coils 121 may be used or alternatively, a variety of other meanssuch as heat exchange fluids in contact with the container or heatexchange medium within the drop tower 116. What is important is that theproduct be cooled but not the reducing metal vapor so that the excessreducing metal in vapor phase can be entirely separated from the productprior to the time that the product exits the drop tower 116 through theproduct outlet 120.

In the example illustrated, titanium tetrachloride and liquid sodiumenter the reactor 115 at a temperature of about 200° C. and titanium andsalt exit the drop tower 116 through product outlet 120 at about 700° C.The excess sodium vapor leaves the dome 118 of the drop tower 116 atapproximately 900° C. and thereafter is cooled in the condenser 137 toform liquid sodium (below 892° C.) which is then recycled to inlet 125.In this manner, dry product is produced, free of liquid reducing metal,without the need of a sweep gas.

Referring now to FIG. 4, there is disclosed another embodiment of theinvention. A system 210 in which like parts are numbered in the 200series as opposed to the 100 series. Operation of the system 210 issimilar to the operation of the system 10 but in the system 210 an inertsweep gas flows co-currently with the product as opposed to thecountercurrent flow as illustrated in system 10 and FIGS. 1 and 2. Inthe system 210 illustrated in FIG. 4, the gas flow is reversed incomparison to the system 10. In the system 210, the sweep gas such asargon, the reducing metal vapor such as sodium vapor and the product oftitanium particles and sodium chloride exit through the outlet 220 intoa demister or filter 250. The demister or filter 250 is in fluidcommunication with a condenser 237 and a pump 240 so that the sodiumvapor and the argon along with whatever fines come through the demisteror filter 250 are transported via a conduit 252 to the condenser 237. Inthe condenser 237, the sodium is cooled and condensed to a liquid, thefines are separated while the argon or inert gas is cooled and recycledvia the pump 240 in line 235 to the drop tower 216. The other apparatusof the system 210 bear numbers in the 200 series that are identical tothe numbers in the system 10 and 100 and represent the same partfunctioning in the same or similar manner.

It is seen that the present invention can be practiced with a sweep gasthat is either countercurrent or co-current with the reaction productsof the exothermic reaction between the halide and the reducing metal orwithout a sweep gas. An important aspect of the invention is theseparation of the reducing metal in vapor phase prior to the separationof the produced metal and the produced salt. When using sodium as thereducing metal, the preferred excess sodium, that is the sodium over anabove the stoichiometric amount necessary to reduce the metal halide, isin the range of from about 25% to about 125% by weight. Morespecifically, it is preferred that the excess sodium with respect to thestoichiometric amount required for reduction of the halide of theelemental material mixtures is from about 25% to about 85% by weight.When magnesium is used as the reducing metal as opposed to sodium, thenthe excess of magnesium in the liquid phase over and above thestoichiometric amount required for the reduction of the halide is in therange of from about 5% to about 150% by weight. More specifically, thepreferred excess magnesium is in the range of from about 5% by weight toabout 75% by weight with respect to the stoichiometric amount requiredfor the reduction of the halide. More specifically, it is preferred, butnot required, that the liquid reducing metal be flowing in a conduit asillustrated in FIG. 2 of the '106 patent previously referred to andincorporated herein by reference.

Various alloys have been made using the process of the presentinvention. For instance, titanium alloys including aluminum and vanadiumhave been made by introducing predetermined amounts of aluminum chlorideand vanadium chloride and titanium chloride to a boiler or manifold andthe mixed halides introduced into liquid reducing metal. For instance,grade 5 titanium alloy is 6% aluminum and 4% vanadium. Grade 6 titaniumalloy is 5% aluminum and 2.5% tin. Grade 7 titanium is unalloyedtitanium and paladium. Grade 9 titanium is titanium alloy containing 3%aluminum and 2.5% vanadium. Other titanium alloys include molybdenum andnickel and all these alloys may be made by the present invention.

In one specific example of the invention, adjustment was made to thesodium flow and temperature by controlling the power to the heater andpump to obtain an inlet temperature of 200° C. at a flow of 3.4 kg/min.This provided a production rate of 1.8 kg/min of titanium powder andrequired a feed of 6.9 kg/min of titanium tetrachloride gas for astoichiometric reaction. The desired feed rate of titanium tetrachlorideis obtained by controlling the pressure of the titanium tetrachloridevapor upstream of a critical flow nozzle by adjusting the power to thetitanium tetrachloride boiler. At this stoichiometric ratio, theadiabatic reaction temperature (1465° C.) is the boiling temperature ofthe reaction product of sodium chloride, and a heat balance calculationshows that about 66% of the sodium chloride is vaporized.

0=ΔH _(reaction) −ΔH _(products) +ΔH _(reactants)

ΔH _(products) =Cp _(ti)(T _(a)−293K)+4(ΔH _(fNaCl) +xΔH _(vNaCl)+(T_(a) −T _(mNaCl))Cp _(NaCll)+(T _(mNacl)−293K)Cp _(Nacls))

ΔHΔ _(reactants) =ΔH _(vTicl4)+(T _(in)−293K)Cp _(Ticl41)+4(ΔH _(fNa)+(T_(in) −T _(mNa))Cp _(Nal)+(T _(mNa)−293K(Cp _(Nas)

where

-   -   DH_(reaction)=−841.5 kJ/mole heat of reaction    -   Cp_(Ti)=28.0 J/moleK solid titanium heat capacity    -   Ta=1738K adiabatic reaction temperature    -   ΔH_(fNacl)=28.0 kJ/mole sodium chloride specific heat    -   x=fraction of NaCl vaporized sodium chloride vapor fraction    -   ΔH_(vNaCl)=171.0 kJ/mole sodium chloride heat of vaporization    -   T_(mNaCl)=1074K sodium chloride melting temperature    -   Cp_(NaCll)=55.3 J/moleK liquid sodium chloride specific heat    -   Cp_(NaCls)=58.2 J/moleK solid sodium chloride specific heat    -   ΔH_(vTiCl)=35.8 kJ/mole titanium tetrachloride heat of        vaporization    -   T_(in)=473K sodium inlet temperature    -   Cp_(TiCl4l)=145.2 J/moleK gaseous titanium tetrachloride        specific heat    -   ΔH_(fNa)=2.6 kJ/mole sodium heat of fusion    -   T_(mNa)=371K sodium melting temperature    -   Cp_(Nal)=31.4 J/moleK liquid sodium specific heat    -   Cp_(Nas)=28.2 J/moleK solid sodium specific heat

Increasing the sodium flow rate to 6.3 kg/min at the same titaniumtetrachloride rate will still give an adiabatic reaction temperature of1465° C. but there will be about 0% sodium chloride vapor present in thereaction zone. Increasing the sodium flow rate above this level willcause a reduction in the adiabatic reaction temperature but at least toa flow of 7.6 kg/min, the reaction temperature will remain above thenormal boiling temperature of sodium (883° C.) and all of the sodiumwill leave the reaction zone as vapor.

Accordingly, there has been disclosed an improved process for making andseparating the products of the Armstrong process resulting from theexothermic reaction of a metal halide with a reducing metal. A widevariety of important metals and alloys can be made by the Armstrongprocess and separated according to this invention.

While there has been disclosed what is considered to be the preferredembodiment of the present invention, it is understood that variouschanges in the details may be made without departing from the spirit, orsacrificing any of the advantages of the present invention.

1. A method of producing an elemental material or an alloy thereof froma halide of the elemental material or halide mixtures comprisingintroducing the vapor halide of an elemental material or halide mixturesthereof into a liquid phase of a reducing metal of an alkali metal oralkaline earth metal or mixtures thereof present in excess of the amountneeded to reduce the halide vapor to the elemental material or alloyresulting in an exothermic reaction between the vapor halide and theliquid reducing metal producing particulate elemental material or alloythereof and the halide salt of the reducing metal and sufficient heat tovaporize substantially all the excess reducing metal, and separating thevapor of the reducing metal from the particulate elemental material oralloy thereof.